A device and method of iterative motion control is described using a non-linear table in a feedback loop to convert a desired acceleration input to motor drive outputs, where the motor is part of a controlled motion system. The table may be a two- or three-dimensional table additionally responsive to the current system state, such as shaft speed, position, or phase angle. The motor may be a two-coil stepper motor where the corrected non-linearity serves the purpose of maintaining desired toque. Inputs may be waypoints comprising both a target position and target velocity. The motion system may use an inverted SCARA arm. Up to three non-linear correction tables may be used: a first corrects motor steps to a more accurate shaft angle; a second corrects motor drive signals to achieve desired torque; a third correct motor drive signals responsive to shaft speed. Tables may be generated by a series of motion passes using a fixed shaft offset angle for each pass.
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1. A method for iterative motion control comprising the steps: (i) accepting an input desired acceleration; (ii) looking up in a first, non-linear table, one or more first table outputs responsive to the input desired acceleration; (iii) outputting one or more motor drive outputs to a motor, wherein the one or more motor drive outputs are responsive to the one or more first table outputs; wherein the one or more motor drive outputs are adapted to control the motor; wherein system state data responsive to the motor is fed back to an iterative real-time controller; and wherein the iterative real-time controller outputs an updated desired acceleration; (iv) iterating steps (i) through (iii) wherein the updated desired acceleration from step (iii) is the desired acceleration in step (i) for each next iteration; wherein the first, non-linear table is additionally responsive to a real-time motor phase angle of the motor.
This invention relates to iterative motion control systems for motors, addressing the challenge of achieving precise and adaptive motor control in real-time applications. The method involves a feedback loop where an initial desired acceleration is input into a non-linear lookup table, which generates outputs based on both the desired acceleration and the motor's real-time phase angle. These outputs are then converted into motor drive signals to control the motor's movement. The system continuously monitors the motor's state data, such as position, velocity, or phase, and feeds this information back to an iterative real-time controller. The controller processes this feedback to generate an updated desired acceleration, which is then used in the next iteration of the control loop. This iterative process allows the system to dynamically adjust motor control parameters in real-time, improving accuracy and responsiveness. The non-linear table ensures that the motor's drive signals are optimized for the current operating conditions, enhancing performance across varying loads and environmental factors. The method is particularly useful in applications requiring high-precision motion control, such as robotics, industrial automation, and high-speed machinery.
2. The method of claim 1 comprising the additional step: (v) accepting a real-time speed of the motor; and wherein the first, non-linear table is additionally responsive to the real time speed of the motor.
This invention relates to motor control systems, specifically methods for adjusting motor operation based on real-time speed feedback. The problem addressed is the need for precise and adaptive motor control to optimize performance, efficiency, and responsiveness in dynamic operating conditions. The method involves using a first, non-linear table to determine a control parameter for the motor, where the table maps input values to corresponding output values in a non-linear fashion. The table is responsive to real-time motor speed, allowing the control parameter to adjust dynamically as the motor's speed changes. This ensures that the motor operates optimally across different speeds, compensating for non-linear characteristics such as torque, power, or efficiency variations. Additionally, the method includes accepting real-time speed data from the motor, which is then used to update the first table. This feedback loop enables continuous adaptation, improving accuracy and performance. The non-linear table may also incorporate other factors, such as load conditions or environmental variables, to further refine control. The system ensures that the motor operates efficiently and reliably under varying conditions, reducing energy consumption and wear while maintaining desired performance levels.
3. The method of claim 1 wherein: the first, non-linear table maps the input desired acceleration to the one or more first table outputs such that the motor generates a torque linearly proportional to the input desired acceleration.
This invention relates to a control system for a motor, specifically addressing the challenge of achieving precise and linear torque output in response to a desired acceleration input. The system uses a non-linear table to map the input desired acceleration to one or more outputs, ensuring the motor generates torque that is linearly proportional to the input. This approach compensates for inherent non-linearities in motor dynamics, such as friction, inertia, and electromagnetic effects, which can otherwise cause deviations between the desired and actual acceleration. The non-linear table is pre-calibrated to account for these factors, allowing the motor to respond predictably and accurately. The system may also include additional tables or algorithms to refine the torque output further, such as adjusting for load variations or environmental conditions. By dynamically mapping the input acceleration to a linear torque response, the invention improves motor control performance in applications requiring high precision, such as robotics, industrial automation, and high-speed machinery. The method ensures consistent and repeatable motion control, reducing errors and enhancing system reliability.
4. The method of claim 1 wherein: the motor is a two-coil stepper motor and the one or more first table outputs comprise two phase angles for the two-coil stepper motor.
This invention relates to controlling a two-coil stepper motor using a table-based approach to determine phase angles for motor operation. Stepper motors require precise control of electrical currents in their coils to achieve accurate positioning and smooth motion. The invention addresses the challenge of efficiently generating the necessary phase angles for driving the motor, particularly in applications where real-time computation may be impractical or resource-intensive. The method involves using a precomputed table of phase angles to control the stepper motor. The table contains one or more sets of phase angles, each set corresponding to a specific motor state or operating condition. For a two-coil stepper motor, the table outputs two phase angles, one for each coil, to determine the current applied to each coil at a given time. This table-based approach simplifies the control logic by eliminating the need for real-time calculations, reducing computational overhead and improving system responsiveness. The phase angles in the table are derived from motor characteristics, such as coil inductance, resistance, and desired torque profiles. By selecting the appropriate phase angles from the table, the motor can be driven with optimal efficiency and precision. The method may also include adjusting the phase angles dynamically based on feedback or changing operating conditions to maintain performance. This approach is particularly useful in applications requiring high-speed or high-precision motor control, such as robotics, automation, and industrial machinery.
5. The method of claim 1 comprising the additional step: (vi) characterizing the motor so as to generate entries in the first, non-linear table; wherein step (vi) is performed prior to step (i).
This invention relates to motor control systems, specifically methods for generating and using non-linear lookup tables to improve motor performance. The problem addressed is the inefficiency and inaccuracies in traditional linear control methods, which fail to account for non-linear characteristics of motors, leading to suboptimal performance and energy waste. The method involves characterizing a motor to generate entries in a first non-linear table, which is done before the motor is operated. This characterization step captures the motor's non-linear behavior under various operating conditions. The method then uses this table to determine a control parameter for the motor based on a measured operating condition, such as speed or torque. The control parameter is adjusted in real-time using a second non-linear table, which compensates for dynamic changes in motor behavior. The system also includes a feedback loop to continuously update the control parameter based on the motor's response, ensuring precise and efficient operation. By pre-characterizing the motor and using non-linear tables, the method provides more accurate and responsive control compared to linear approaches, improving energy efficiency and performance. The invention is particularly useful in applications requiring high precision, such as industrial automation, robotics, and electric vehicles.
6. The method of claim 5 wherein: the characterizing the motor step comprises a sequence of motor movements, wherein each motor movement in the sequence comprises a fixed phase offset angle for that movement; wherein acceleration of the motor during each motor movement in the sequence is recorded; and wherein each motor movement in the sequence comprises a different fixed phase offset angle.
This invention relates to motor control systems, specifically methods for characterizing motor performance by analyzing acceleration during controlled movements. The problem addressed is the need for precise motor characterization to optimize performance, detect faults, or calibrate systems in applications like robotics, automation, or industrial machinery. The method involves a sequence of motor movements, each with a distinct fixed phase offset angle. During each movement, the motor's acceleration is recorded. By varying the phase offset angle for each movement in the sequence, the system captures how the motor responds under different conditions. This approach allows for detailed analysis of motor behavior, including torque variations, mechanical inefficiencies, or alignment issues. The recorded acceleration data can be used to generate a performance profile, identify anomalies, or adjust control parameters for improved operation. The sequence of movements ensures comprehensive testing by systematically altering the phase offset, which may correspond to rotational positions or timing adjustments. The recorded acceleration data provides insights into dynamic motor characteristics, such as response time, stability, and consistency. This method is particularly useful for motors operating in environments where precise control and reliability are critical. The technique can be applied during manufacturing, maintenance, or real-time monitoring to ensure optimal motor function.
7. The method of claim 1 comprising the additional step: (vii) accepting a real-time motor shaft angle indication; (viii) looking up in a second, angular position correction table, a second table output: a corrected shaft angle, responsive to the real-time motor shaft angle indication; (ix) computing a motor shaft angular velocity responsive to the corrected shaft angle.
This invention relates to motor control systems, specifically improving the accuracy of motor shaft angle and angular velocity measurements. The problem addressed is the inherent inaccuracies in real-time motor shaft angle readings, which can lead to errors in calculating angular velocity, affecting motor performance and control precision. The method involves a multi-step process to correct these inaccuracies. First, a real-time motor shaft angle indication is received from a sensor. This raw angle reading is then used to look up a corrected shaft angle in a second angular position correction table. The correction table compensates for known inaccuracies in the sensor or mechanical system, providing a more accurate shaft angle. Next, the corrected shaft angle is used to compute the motor shaft's angular velocity. This corrected velocity can then be used for precise motor control, such as in servo systems, robotics, or other applications requiring high accuracy. The correction table is pre-populated with data that accounts for systematic errors, such as sensor misalignment, mechanical backlash, or other sources of inaccuracy. By applying this correction, the system achieves more reliable and precise motor control. The method is particularly useful in applications where small errors in angle or velocity can lead to significant performance degradation, such as in high-precision manufacturing or robotic systems.
8. The method of claim 7 wherein: the motor is a stepper motor; the real-time motor shaft angle indication is a step number of the stepper motor.
A system and method for controlling a stepper motor to achieve precise angular positioning. The invention addresses the challenge of accurately determining and controlling the rotational position of a stepper motor in real-time, which is critical for applications requiring high precision, such as robotics, automation, and positioning systems. The method involves using the step number of the stepper motor as a real-time indication of the motor shaft angle. The step number represents the discrete rotational increments commanded to the motor, allowing for direct correlation to the shaft's angular position. This approach eliminates the need for additional sensors or complex feedback mechanisms, simplifying the system while maintaining accuracy. The stepper motor is controlled by generating step pulses that correspond to specific angular displacements, and the cumulative step count is used to track the shaft's position. The method ensures that the motor's rotational position is known at all times, enabling precise movement and positioning. The invention may also include a controller that processes the step number data to adjust motor operation dynamically, ensuring consistent performance under varying load conditions. This solution provides a cost-effective and reliable way to achieve accurate angular positioning in stepper motor applications.
9. The method of claim 7 wherein: the second, angular position correction table correct for an eccentricity between the real-time motor shaft angle indication and actual motor shaft angle.
A system and method for correcting angular position errors in motor shaft angle measurements. The technology addresses inaccuracies in real-time motor shaft angle indications caused by mechanical misalignments, such as eccentricity, which introduce discrepancies between the measured and actual shaft angles. The method involves using a second angular position correction table specifically designed to compensate for these eccentricity-induced errors. This correction table is applied to the raw motor shaft angle data to adjust the real-time indication, ensuring it more accurately reflects the true angular position of the motor shaft. The correction process may involve mapping the measured angle to a corrected angle based on predefined relationships stored in the table, which are derived from calibration or empirical data. The system may also include additional correction mechanisms, such as a first correction table for other types of angular errors, ensuring comprehensive compensation for all sources of measurement inaccuracies. The overall goal is to improve the precision of motor control and monitoring systems by minimizing angular position errors, which is critical for applications requiring high accuracy, such as robotics, industrial automation, and precision machinery.
10. The method of claim 1 wherein: the iterative real-time controller is adapted to accept a sequence of goal waypoints wherein each waypoint in the sequence comprises a goal position and a goal velocity.
A method for controlling a system in real-time involves an iterative controller that processes a sequence of goal waypoints, where each waypoint includes both a target position and a target velocity. The controller adjusts the system's operation to reach these waypoints dynamically, ensuring precise tracking of both position and velocity over time. This approach is useful in applications requiring high-precision movement, such as robotics, autonomous vehicles, or industrial automation, where maintaining both position and speed accuracy is critical. The iterative nature of the controller allows for continuous adjustments based on real-time feedback, improving responsiveness and adaptability to changing conditions. By incorporating velocity as part of the waypoint definition, the method ensures smoother transitions between targets and reduces overshoot or oscillation, enhancing overall system performance. The controller may use feedback mechanisms, such as sensors or predictive algorithms, to refine its adjustments and maintain alignment with the desired trajectory. This method addresses challenges in systems where traditional position-only control may lead to inefficiencies or inaccuracies, particularly in dynamic environments. The inclusion of velocity in the waypoint definition allows for more nuanced control, enabling the system to anticipate and respond to changes more effectively.
11. A device implementing the method of claim 1 .
12. A system implementing the method of claim 1 ; further comprising the motor and the iterative real-time controller.
A system for controlling a motor in real-time to achieve precise positioning or motion involves an iterative real-time controller that adjusts motor operation based on feedback. The system addresses the challenge of maintaining accurate motor control in dynamic environments where external disturbances or varying loads can disrupt performance. The iterative real-time controller continuously monitors motor behavior, compares it to a desired state, and adjusts control parameters in real-time to minimize errors. This iterative process ensures that the motor operates efficiently and accurately, compensating for disturbances without requiring pre-programmed adjustments. The motor itself may be any type of actuator, such as a servo motor, stepper motor, or linear motor, depending on the application. The system is particularly useful in industrial automation, robotics, and precision machinery where consistent and reliable motor performance is critical. By dynamically adapting to changing conditions, the system improves reliability and reduces the need for manual calibration or intervention. The iterative real-time controller may use algorithms such as model predictive control, adaptive control, or machine learning to refine motor commands based on real-time feedback. This approach ensures that the motor maintains optimal performance under varying operational conditions.
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April 26, 2017
November 26, 2019
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